fix(rest): thread ?mode=draft on the compound-name metadata write door (#11933)

* fix(rest): thread ?mode=draft on the compound-name meta write door

Part of #11712.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019siH5jDmk5hrayvfyojUqR

* test(rest): pin the compound door's draft/publish parity; record the new engine double

Part of #11712.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019siH5jDmk5hrayvfyojUqR

* docs(changeset): name the missing compound-arity REST promotion door

Part of #11712. The changeset becomes CHANGELOG.md, so a consumer who starts
using ?mode=draft on a compound name learns from the same paragraph that the
per-item REST promotion door does not exist in that arity yet (#11932).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019siH5jDmk5hrayvfyojUqR

---------

Co-authored-by: Claude <zhuangjianguo@steedos.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: 3 people

.changeset/compound-meta-door-mode-draft.md

@@ -0,0 +1,52 @@
+---
+'@objectstack/rest': patch
+---
+
+fix(rest): `?mode=draft` now stages on the compound-name metadata write door
+
+`PUT /api/v1/meta/:type/:section/:name` — the compound-name door, the one you
+reach with a name like `views/all_leads` — built its `saveMetaItem` request
+field by field and `mode` was not one of the fields. Its single-segment twin
+`PUT /api/v1/meta/:type/:name` has read that parameter all along. The parameter
+was never refused here, only dropped, so the request was answered `200` and
+published **live**. Both doors now read it.
+
+**Two behaviour changes, and both can be observed by an unchanged caller.**
+
+**1. `?mode=draft` on this door changes OUTCOME, not acceptance.** The request
+was accepted before and is accepted now; what moved is what it does.
+
+| Request | Before | After |
+| --- | --- | --- |
+| `PUT /meta/object/crm/task?mode=draft` | `200`, `"state":"active"` — the live row overwritten, nothing staged | `200`, `"state":"draft"` — a staged row written, the live row untouched |
+
+If you send `?mode=draft` to a compound name today and rely on the write going
+live — for instance because you never call `POST /meta/:type/:name/publish` —
+those writes stop taking effect immediately and start waiting for a promotion.
+Drop the parameter to keep publishing straight away. `mode=publish`, an
+unrecognised `mode=`, an empty `mode=` and no `mode` at all are all unchanged:
+they publish, exactly as before. The spelling test is the twin's, `draft`
+case-insensitive.
+
+⚠️ **The draft you can now stage has no per-item REST promotion door in this
+arity.** `POST /meta/:type/:name/publish` is mounted for single-segment names
+only, while its read twin `GET /meta/:type/:section/:name/published` is mounted
+for both — so a compound-named draft is writable and readable over REST and not
+promotable there. Until that route exists, promote through
+`POST /packages/:id/publish-drafts` (whole-package) or the runtime dispatcher's
+own `meta.publish` verb. Tracked in #11932; this release does not change it.
+
+**2. A repeated `?mode` is now REFUSED where it was accepted.** This narrows
+what the door takes. `?mode=draft&mode=draft` arrives as an array; the
+`typeof === 'string'` test is false for it, so before this change it fell back
+to publishing live under a `200`. It is now answered `400`
+`{ "error": { "code": "VALIDATION_ERROR" } }` and nothing is written — the
+#6877 guard this door already applied to `force` and `package`, extended to the
+parameter it just gained, and the same answer the single-segment twin has given
+for a repeated `mode` since #6877. A single occurrence encoded as an array
+(`?mode=draft` once) is still accepted; the guard unwraps rather than
+blanket-refusing.
+
+Nothing else on the door moved: `?force`, `?package`, the `meta-envelope`
+write face, the `manage_metadata` gate and the `501` envelope are untouched,
+and the single-segment twin is untouched.